These motor mount spacers are cut from card which is 0.3mm thick making them perfect for making fine adjustments on motor mounts. Most motor mount spacers are cut from 0.5 or 1mm sheets and don’t allow for finer adjustments in the packing thickness. With these 0.3mm spacers however you can use multiple spacers glued together and stacked one on top of the other to achieve 0.3mm, 0.6mm 0.9mm and so on packing thicknesses.